Improving performance when quering information_schema

When running on a database server with a large information_schema database, this query is abnormally long, optimised per http://dev.mysql.com/doc/refman/5.6/en/information-schema-optimization.html
Maybe add this as extra constraint to the JOIN clause in stead of the WHERE? I.e.

ON (kcu.CONSTRAINT_NAME = rc.CONSTRAINT_NAME AND kcu.TABLE_NAME = rc.TABLE_NAME)

Not tested if this results in the same performance gain, but seems like a cleaner solution.

(Sorry added my comment on the commit in stead of the PR first time)